Apparatus for producing musical tones



2 Sheets-Sheet l INVENTOR ATTORNEY v R'H. RANGER APPARATUS FOR PRODUCING MUS-ICAL TONES Filed Oct 29, 19:52

Fig.3

Oct. 29, 1935. 3

Oct. 29, 1935. t H. RANGER 2,018,924

I APPARATUS FOR PRODUCING MUSICAL .TONES Filed Oct. 29, 19:2 v 2 Sheets-Sheet 2- I 1 TOR.

ATTORNEYS.

UNITED' STATES PATENT OFFICE l'ollml mcmc MUSIC W Rowland N. J. Application mm :0. 193:, Serial misuse:

The present invention relates to electrical apparatus for producing musical sounds. The invention has been developed more particularly in connection with the construction of an apparai tus for producing chimes and such an embodiment will he -described for the of illustrating the principles involved, but it will be understood that the particular description is 11- lustrative merely and is not intended as defining i the limits of the invention. a

In apparatus of the type to be described, a musical note is produced by impreming upon the grid of an amplifier a voltage which is varied in accordance with the quality of the note desired. 11,

i for example, a pure fundamental tone is desired; the voltage impressed upon the grid may be an alternating voltage or an oscillatory voltage in which the alternations follow substantially the sine curve pattern. If a note of more complicated 0 tonal structure as, for example, one including the fundamental and overtones or a number of overtones without the fundamental. is desired, the pattern of the voltage oscillations becomes more complicated but the principle involved is the same. Several methods of impressing the desired voltage variation upon the grid have been pro- The present invention has for an object to provide an improved arrangement for impressing structure can be changed after anote is struck and while it is still sounding.

"A further and important object consists in manufactured. a The nature and various objects of the inven- -tionjwiil be better understoodfrom' a description illustrative embodiments for the.

of which description reference should 50 behadtothe'accompanyingdrawingsforminga and in whichl isanelectricaldiagramof minus hook-up embodyin the invention.

11 1;: is a detail view'showing a simple-fem N. condenser,

- upon the grid an alternating voltage according to ('01. va l-1i Fig. 3 shows an illustrative chime operating mechanism,

Fig. 4 shows a manually operate device for'a single chime note,

Fig. 5 isadetail viewshowingmeansforhold- 5 ing the plucking element retracted.

Fig. 6 is an electrical diagram showing a chime hook-up, and' I Fig. 7 is a detail view of another form of pick-up embodying one feature of the invention. l0

In accordance with the present invention a variable condenser is employed in a suitable circult to effect the desired alternating voltage. In the illustrative arrangement to be more p'articularly described, a suitable generator capable of providing a relatively high potential, a relatively large resistance and a variable condenser are connected in series to provide a direct current circuit which is open at the condenser, but which upon I an oscillatory variation of thelcapaoity of the condenser will cause a variation '..of voltage of alternating character. This varying voltage is referred to in this description as an alternating voltage" regardless of the fact that its average maybe other than zero. Such alternating voltas age is impressed upon the grid oihan audio irequency ampliilen, the connection ordinarily in- .cluding a coupling condenser permitting the passage of the alternating but not of the direct.

Referring more particularly to the drawings.

Fig. l is an'eiectrical diagram of an arrangement for producing a pure fundamental tone or a note combining a fundamental and overtones. A generator arranged to develop a voltage of the order of 200 volts andv indicated conventionally as a battery 5 is connected in circuit with a resistance 0 which may be of the order of 2 or 3 megohms and a variable condenser l which mayhave, for egample, a'capacity of the order of 0.0005 microfarads.- The generator is preferably, but not 40 necessarily, arranged with its positive terminal connected to the resistance and the connection to the grid is preferably extended from between'the resistance and the condenser as indicated in the diagram. Upon oscillatory variation of the ca- 40 I pacity of the condenser at, for example, audio frejquencies, an alternating current will'be induced in the andwhat ismore important in connection with the present invention, an alternating voltage will be induced in'the conductor I between the'conden'ser andthe resistance. This alternating'voltage is the ma 0 -ofanamplifyingtube l0. A'coupling condenser II is shcwn between the source of-alternative voitageand thegridinorder alternating voltage is thus impressed upon the grid 8. the amplifier tube if energized will produce a fundamental tone in the ear phones conventionally illustrated at If, the filament l3, condenser I4 and plate ll performing their functions asusualindevicmofthistype. Abiasresistance ll and, if'desired, a bias battery may be introducedbetween thegridandfilamentasusualto maintain the grid at the desired voltage, usually slightly below zero. v

Thebias resistance and the filament, especially ifgrounded',mayalsobeconnectedtotheoneside of the battery I, as indicated in the drawings.

The alternating voltage to be impressed on the grid is set up by oscillatory variation of the capacity oi" the condenser 'i. The arrangement shown is intended primarily for producing musical sounds and for this p rpose the rate of change of the capacity of the condenser should be of audio frequency. Accordingly in this description, the condenser will be described as variable at an audio frequency rate. It will be understood, however, that this description is illustrative merely; the operability of the arrangement shown is not limited to frequencies which are in fact audible to the human ear.

As a convenient arrangement for varying the capacity of the condenser at an audio frequency, at least one of the condenser plates is formed as a vibrating reed and suitable means isprovided for causing the desiredvibration. In Fig.2 is shown a simple condenser consisting of two plates I1 and it one of which is a vibratory reed and the other of which is adjustable by a set screw is to varythenormal capacity of the condenser and therefore the voltage induced and the loudness of, the note produced. The condenser I of Fig. 1 is substantially the same in principle but consists of a longitudinally adJustable condenser plate 20 with two vibratory reeds Ii, 22 of diiferent periods of oscillation. Either reed-may be vibrated alone to produce a corresponding fundamental or both may be vibrated together to produce a note comprising a fundamental and two or three overtones. In the arrangement shown the reeds vibrate directly toward and from the companion relatively fixed plate as distinguished from an arrangement 1 in which the movement is in the plane of the plate but so arranged as to increase and decrease the capacity of the condenser. The sound and the damping effect vibrating in air is probably greater in this arrangement, but it is not ordinarily objectionable. It will be understood that means may be provided for maintaining continued vibration as by an airblsst but such continued vibration is not desired in the arrangement herein described. The amplitude of vibration must be such that there is no contact between the plates for obvious It'willbe noted that one condenser element, for this example the vibratory reeds may be grounded and theotherelementinthatcasemustbeinsulated for obvious reasons. Aseither-or bothreedsare vibrated. the note becomes audible-in the ear phones It. It is usually-desirable, however, to"

amrflify' the note further to p rate a loud speaker practice Y insecordaneewithusual .In chimes, as illustrative of various types of musical notes, a complex harmonic structure is desired rather than a pure fundamental note.

Thenote ofbell chimes usually contains as its outstanding components or frequencies a fundamental andits overtones-Ill. 2, 8,4, 8, I55, 8, l, I andI. Thecchimesofthistypemaythenbepro duced in accordance with the principle embodied in the diagram of Fig. l by providing a number of voltage inducing circuits of the type described and impressing all of the alternating voltages thur set up on the grid 8. In the several circuits .the reeds of the respective condensers would be tuned to the frequencies of the fundamental and overtones respectively and the fixed plates of the respective condensers would be adjusted in accordance with the intensity of the respective overtone in the chime note. Certain of the overtones, however, are of minor importance and for practical purposes it is sufilcient to select, for example, the fundamental and two or three of the more important overtones, as the sufficient components of the synthetic chime note.

The several component frequencies are preferabLv of difi'erent amplitudes to produce the desired tonal structure. For this reason the amplitude of each should be determined by suitable adjustments. The amplitude of the alternating voltage can be varied by modifying the amplitude of oscillation orthe reed, by suitable variations of the normal capacity of the condenser, by variation of rangernent of theresistance.

It is not necessary that several, in this case twelve, entirely separate circuits be employed for producing the several alternating voltage components. Instead one battery and one principal resistance may be suiiicient.

. It is even possible to provide one large fixed condenser plate and several reeds opposite it and in'the same circuit. There are, however. compensating advantages in providing at least sepa-. rate condensers, each comprising a relatively fixed plate and a vibratory plate or reed.

The voltage output from enumber of reeds can be impressed upon the grid of one amplifier but better results are obtained if onlya limited number of reeds are connected to impress their respective alternating voltages upon one grid. An octave of 12 notes may ordinarily be handled by one amplifier tube. The output fromseveral tubes can be placed in parallel in an appropriate combining transformer in accordance with known practice.

In Fig. 6 is illustrated an electrical diagram of an arrangement forwestminster chimes in which the notes a, c, d, e are each compounded of l the fundamental, the eighth and the twelfth, being respectively and'accurateLv the first, second and third multiples of the fundamental. The

fundamental tones of the respective notes are produced through condensers 26, 21, I8 and 28, all connected to the variable resistance or potentiometer 30. The first overtone condensers II, 32, I8 and 34 are similarly connected to the resistance SI and the second overtone condensers 36, 31, 38 and It to the variable resistance II. By 6 arrangement the condensers of the funda-.

mental tones will all have the same resistance in their respective circuits and so too with each of the overtones. The resistances provide means for varying the voltages at the condenser and indi- 6 rectly the voltages of the alternating voltage components impressed upon the arid and therefore of the corresponding componentsof the note. The desired tonal structure may therefore be obtained by adjustment of the resistances. The tonal 7' quality of the four notes will be of, the same synthetic character for the reason that the overtones in each case have the same relative strength and therefore the same influence on the tone quality. The fixed condenser elements are pref- 1| aoiaeas erabl! adjustable even in this arrangement in order that further individual adjustments may be made as desired. As indicated in the diagram.

a resistance II. is connected between the delivery side of the condensers and the negative terminal or the battery. the variable re 80, I! and ll acting as potentiometers being connected between the opposite side of the condenser and the other terminal of the battery. It will be obvious that the amount of resistance introduced by the variable resistances and the ratio between it and the main resistance will determine the strength of the alternating voltage impressed upon the grid. Condensers 45, 48 and 41 are introduced in the resistance circuits as indicated for the'purpose .of smoothing out any variations in the supply voltage from the battery. The free ends of the resistances 30, 35 and are grounded and the circuit is also grounded at a suitable point as, for example, between the resistance ll and the battery, as indicated at 4B. Inasmuch as the amplifying tube of this figure may be an exact duplicate of the amplifying tube oi'- Fig. l, the same reference characters are applied to the corresponding parts.

In Fig. 4 there is shown apparatus for manually operating chimes, certain novel controlfeatures being embodied therein. The mechanism for one note only is shown as sufilciently illustrating the structure.

In this arrangement the one chime note comprises a fundamental and three overtones. Accordingly there are four condensers consisting of .four vibratory reeds 50 and four separate relatively fixed plates 5|. A plucking device is provided for plucking the four reeds simultaneously. As shown, a key 52 operates a striking rod 53 which engages at its lower end and operates a centrifugal force as it swings about'its pivot, will engage the reeds while moving'through a greater are and will, therefore, pluck more violently to provide a greater amplitude of vibration. The action of the plucking element against the reeds tends to force it back toward its pivot, so that, upon its return movement, it will not again engage the reeds. It is, however, desirable to insure the retraction of thepiucking element and to prevent its too immediate return to its outermost position,-as for example, by the arrangement indicated in Fig. 5, in which a spring wire loop 59,

engages a sloping projection 60. The spring loop 59 is adjusted to engage the plucking element at about the time that the reeds are plucked and to maintain contact therewith during a small portion of the return movement. The spring loop may furthermore be tensioned to quicken the re- .turn movement of the plucking device. This arrangement provides for the plucking of the reeds more or less actively by a perfectly natural more or less vigorous striking of the key 52-. In its lowermost position the plucking member rests upon a stop 62. The relatively fixed element'sfof the condensers are formed as separate parts electrically insulated from each other rather than as one integral structure, in order that the arrangement maybe satisfactorily employed in a. circuit ofthe type iliustrated'in 1'18. 6, wherein different resistances are connected with the several plates It is a feature-of the arrangement shown in 5 Fig. 4 that theintensity'of the note can befurther modified at will to provide, for 'exasnplqa finger controlled i This is ,accompiished by imposing a'difie'rence of capacity upon the condensers. The simple method shown consists of movement of the relatively fixed elements of the respective condensers toward the vibrating elements.

The so-called fixed condenser elements are carried in the insulating block es which in turn 18 is movably. supported by spring 8' secured to the framework. An arm 01 pivoted at II is engaged by an adjustable collar 89 on the striking rod 53. when the key 52' is held in its lowermm position, the arm 61 by engaging the arm 10 2Q projecting from the block 85 will move the fixed condenser elements toward thevibratory reeds. A damping member is also carried by the arm, 61 in position to engage and damp the vibrating reeds when the key 52 is entirely released. Itis '25 desirable to provide means whereby the damping member may be held in inoperativeposition independently of the operation of the keys and toprovide means for moving the fixed condenser elements toward the reeds and holding them in adjusted position. To this end an eccentric member 18 is positioned to engage the lower extension of the arm '61. A small partial rotation of this eccentric will withdraw the damping element from contact with the reeds and a further move- 85 merit will move the fixed condenser members by engagement of the arm 61 with the arm Ill. The eccentric may then be held fixed in any desired position to effect correspondingly the intensity of the note.

In Fig. 3 there is shown atically-an automatic arrangement for operating chimes of a type embodying the invention herein described. In this arrangement a drum- 80 is rotated by a small electric motor 8i through-suitable worm'45 gearing. The drum shaft '82- carries a motor control cam 83 and a filament control cam 84. The motor control cam carries, a riser'engage'abie with a follower I5 to open the motor control cir cult switch as. A push button in (which'is merely representative of any hand or automatic switch) is provided for starting the motor. This switch need be held closed only until thecam riser releases the follower to permit closing of the motor control switch. will then make one complete rotation until the riser again opens the control switch. The earn as will close the circuit througli the battery as.

and the filament 8B of the amplifier while the tone control circuits are energized in the same manner as above described.

The drum 80 carries plucking pins Oil engageable with corresponding reeds 9| of suitably arranged condensers Of a chime arrangement constructed in accordance with the principles hereinabove outlined. The plucking pns and reeds may be arranged in accordancev with the notes desired following the well-known principles of music box construction. Thearrangement diagrammatically illustrated is merely suggestive.

It isimportant that the several reeds of each chime note may be plucked simultaneously. It is impossible mechanically to obtain absolute accuracy. In order to increase the accuracy of such simultaneous striking, the;drum is some- [I The drum and cam what yieldably connected to its shaft, whereby asonereedofasetslipsfromthe plucking pin, the drum may have a tendency to move quickly forward thereby to more immediately P uck the other reeds.

' To this end a rubber connection is provided between the drum and shaft. In the structure illustrated a resilient rubber member 92 is secured to the shaft and engages between four pins 83.

Each time that the chimes are sounded, the drum 80 makes I a complete rotation and the plucking pins engageall of the reeds. The control to provide for sounding the chime is obtained by lighting the filament of the amplifier under control of the chime control cam 84 when the shaft starts turning. This cam is arranged to close the filament circuit and to cause it to be maintained closed for only a suilicient length of time to provide for the sounding of the desired notes. A condenser 95 is placed across the filament terminals in order to prevent too abrupt a breaking of the circuit through the filament. This condenser should be of a capacity of the order of 2000 micro-farads, forexample, an

electrolytic condenser such as is well known in the art. The switch arrangement controlling the filament circuitmay be of any suitable construction. When the riser of cam 84 again engages the follower the circuit is again opened,

but the filament will dim gradually due to the effect of the, condenser, thereby preventing an unpleasant sound. v

It is a feature of the invention that the intensity of the note as a whole or the intensity of a component may be varied in accordance with my desired pattern.

In the manual operation arrangement of Fig. 4 the fixed condenser plates are moved manually toward and from the vibrating reeds under control of the finger on the key to provide a tremulo or other desired efi'ect. In the mechanical control of Fig. 3, a cam control providing as an example oi' tremulo. As a pleasing variation only one of the component tones, preferably the fundamental, is given the tremulo 'efiect by movement of its condenser plate. It is one of the novel features of the invention that this particular type of tremulo sheet is provided. Essentially this is accomplished by providing means for producing more or less independently the component tones with means for independently varying the intensity of at least one component without varying the intensity of all the components. The principle involved can of course be carried much further and other types of variations of one or -more of the component tones can be varied in numerous ways in pitch or intensity. From the condenser plate for the fundamental an arm 08 projects into engagement with a cam 01 formed on the drum. -This cam may provide. for example, a tremulo as indicated or it may be designed to eflect only an increase or 'only a decrease of intensity ofinote. I

' Thisfeature of the invention is applicable to other arrangements than that herein described,

in which a variable condenser controls the alternating voltage impressed on the grid. This will be more clear if we consider the reed broad- .ly as'a vibratory element and the opposed condenser plate as a pick-up element. The intensity of the voltage induced is then increased and reduced as the pick-up element is movedtoward and from the vibratory element. various pleas- JIH eifects, of which the tremulo is im example,

, character in which the pitch of the note is varied.

This is accomplished by introducing an influence to change the rate of vibration of one or more of the reeds. The principle involved is illustrated 1| in Fig. 3, wherein two reeds 98 of one chime note are of magnetic material and are subjected to the action of an electromagnet-l l and wherein soft iron inserts IIO in the drum III pass close to the ends of the reeds at suitably spaced intervals to ll modify the rates .of vibration and provide a pleasing tremulo. Each insert temporarily closes the magnetic circuit through two reeds.

This feature also is applicable to other types of pick-up, wherein a vibratory reed and a pick- 21 up element are arranged to produce an alternating voltage which is impressed upon the grid.

v The three plate condenser I as indicated in Fig.

1 comprising two vibrating reeds produces a novel effect in that alternating voltages of three or four 2: different periods may result; to wit, those having the frequency of the two differently tuned'reeds and those having frequencies corresponding to the sum and difi'erence of the two frequencies. If the reed frequencies are of 2 to 1 ratio the differ- 3i] ence is, of course, thesame as the lower reed free quency. Y

The principle involved wherein two reeds of different frequencies are vibrated adjacent each other to provide a note having both frequencies 85 and additional overtones can be otherwise applied. For example, as indicated in Fig. 7, the two reeds IUI, I02 of magnetic material having frequencies related in the ratio of 3 to 1 may be connected to a magnetic core III! of a coil I with 0 the free vibrating ends spaced but overlapping. Either reed may be vibrated to cause an alter nating voltage of corresponding frequency or both may be vibrated to produce a complex alternating voltage having four frequency comto ponents of the ratios 1, 2, 3 and 4. Such an arrangement produces a note having a certain definite quality.

The .foregoing particular description is illustrative merely and is not intended as defining the 50 limits of the invention. It will be understood that the principles of the invention can be variously embodied and the embodiments described can be variously modified without departing from the spirit of the invention, as'defined in the apvpended claims. v

I claim:

1. In apparatus for producing musical sounds in combination an audio frequency amplifier having a grid, and means for impressing upon the grid an alternating voltage'of audio frequency comprising an electric circuit including in series a high voltage current generator, a resistance and 'a variable condenser oneplateot which consists I 'of a vibratory element comprising magnetic ma-' terial and having a period of vibration correspondingto the frequency of tone to be produced, to-

gether with means for setting up a magnetic field through said element and means for periodically introducing magnetic material into said field ior varying theimpedance in said field and thereby modifying the rate of vibration of said vibra-'- tory element. a

3. In apparatus for producing musical sounds, the combination with a vibratory element having a period of oscillation corresponding to atone to be produced of a pick-up element and means cooperating with the vibratory element for producing electrical response in the pick-up devicetogether with magnetic means for varying the period of oscillation of the vibratory element to produce a tremulo.

4. In apparatus for producing musical sounds, in combination, a reed, a manually operable key, a plucking element operatively connected to said key for actuating said reed and means causing 'said plucking element to be projected more or less toward the reed to pluck the same more or less' actively as the key is actuated more or less rap 5. In, apparatus for producing musical sounds,

in combination, a reed, a manually operable key,

a plucking element, operatively connected to said key, for actuating said reed, said plucking element being piv'otally supported for movement in an arc with spring means yieldably drawing it toward the point of pivotal support and so tensioned that when actuated more or less rapidly it will move radially from the pivot more or less under the action of centrifugal force and engage the reeds more or less eiifectively.

6. Apparatus for producing musical sounds, as defined in claim 5, wherein means is provided for holding the plucking element radially inward after I its operative engagement with the reeds.-

'7. In apparatus for producing musical sounds,

in combinatioma reed, a manually operable key, a plucking element operatively connected to said key for actuating said reed, a pick-up element positioned adjacent said reed, and means operatively connected to saidkey-to be actuated when said keyisnearitsextremeoperativepositiontoremusical note comprising one or more overtones ment having a period of oscillation correspondpick-up device together with magnetic means for varying the period of oscillation of the vibraothers in accordance jduce the distance between the vibratory reed and the pick-up device to increase the over-all response.

- 8. In apparatus for producing musical sounds. the combination with an amplifier having a grid of means for impressing an alternating voltage on said grid comprising a condenser having two vibratory elements of different periods of oscillation with, a .third element therebetween and means cooperating with the condenser including an electric circuit to pick-up the vibrations and produce an alternating voltage compounded oi the ,trequencies of the two vibratory elements and theirequencies corresponding to the sum and difference of said first mentioned frequencies. v

9.- In apparatus for producing musical sounds the combination with means for producing the component tones simultaneously to produce a of means for varying the intensity of one component relative to the intensity of the other or others to provide a tremulo eiIect.

10. In apparatus for producing musical sounds, the combination with a vibratory eleing to a tone to be "produced of a pickup element and means cooperating with the vibratory element for producing electrical response in the tory element in accordance with a mined pattern. v

ii. In apparatus iorproducing musical sounds the combination with means for producing the component tones simultaneously to produce a musical note comprising one or more overtones of means for varying the intensity of one component relative to the intensity of the other or predetercomponent tones simultaneously to produce a musical note comprising one or more overtones 5 of means for varying one component relative to the other or others to' provide a tremulo.

nrcman nowLANn' mom.

a predetermined pat- 4o 

